This invention relates to a detector for force, acceleration or magnetism, and more particularly to a detector capable of obtaining detection values every respective components in multi-dimensional directions.
In the automobile industry, or machinery industory, there has been an increased demand for detectors capable of precisely detecting a physical quantity such as force, acceleration or magnetism. Particularly, miniaturized detectors capable of detecting such physical quantities every respective components in two-dimensional or three-dimensional directions are desired.
In order to cope with such demand, there has been proposed a detector for force/acceleration/magnetism in which gauge resistors are formed on a semiconductor substrate such as silicon, etc. to transform a mechanical distortion produced in the substrate on the basis of a force applied from the external to an electric signal by making use of the piezo resistance effect. However, such detector using gauge resistor has the problem that the manufacturing cost is high and any temperature compensation is required.
In view of this, in recent years, there has been proposed a detector in which capacitance elements or piezoelectric elements are used to carry out detection of a physical quantity. For example, in the U.S. patent application no. 07/761,771 (European Patent Application No. 91900948.0), a novel detector utilizing changes in the electrostatic capacity has been proposed. In this novel detector, a capacitance element is constituted by a fixed electrode formed on a fixed substrate and a displacement electrode producing a displacement by action of a force. Respective components in multi-dimensional directions of an applied force can be detected on the basis of changes in the electrostatic capacity of the capacitance element. Further, in the U.S. patent application no. 07/764,159 (European patent application no. 91117418.0), a method of manufacturing such a novel detector is disclosed. In the No. PCT/JP91/00428 according to the International Application based on the Patent Cooperation Treaty, a method of testing or inspecting such a novel detector is disclosed. In addition, in the No. PCT/JP92/00882, a detector using piezoelectric element in place of capacitance element is disclosed.
In the above-described detectors, a plurality of capacitance elements or piezoelectric elements are arranged in a two-dimensional manner to detect components in multi-dimensional directions of a physical quantity in an XYZ three-dimensional coordinate system. Namely, detection elements for detecting a physical quantity in the X-axis direction are arranged on the X-axis, and detection elements for detecting a physical quantity in the Y-axis direction are arranged on the Y-axis. Generally, since such a detector for physical quantity is required to be miniaturized, the area where respective detection elements can be arranged is limited. Accordingly, in order to permit the detection elements for the X-axis and the detection elements for the Y-axis to be independently arranged, the detection effective area (the area directly related to the detection sensitivity of a physical quantity, e.g., the electrode area constituting capacitance elements) for respective detection elements cannot but be limited. For this reason, there was the problem that according as miniaturization of the detector is made to more degree, the detection sensitivity is lowered accordingly.